This invention relates to low tantalum content cobalt-base alloys.
In one of its more specific aspects this invention relates to articles made from such alloys, particularly articles made by casting.
In certain industrial applications, there is a need for alloys which possess high rupture strength and high oxidation resistance at high temperatures. Among such applications are those involved, for example, in the glass fiber industry, where filaments are produced by passing a molten material, for example, glass, through the foraminous walls of a chamber adapted for rotation at high speeds, the chamber being known as a spinner, the filaments being emitted through the apertures of the wall due to the centrifugal action to which the molten material is subjected upon rotation of the spinner. Such spinners are usually operated when spinning glass fibers at temperatures of about 2,050.degree. F. and rotational speeds of about 1,700 RPM. Under these conditions, the alloy of this invention has been found to possess superior stress-rupture and creep properties and superior resistance to the molten glass environment to which it is subjected.
One of the best materials known for use in such applications is that defined and claimed in U.S. Pat. No. 3,933,484 issued Jan. 20, 1976. That alloy contains on a weight basis from about 1.4 to about 6.5 percent tantalum. However, tantalum is very expensive and because significant quantities of tantalum are lost during the preparation of the alloy, amounts greater than the defined amounts must be used in achieving the ultimately desired tantalum content in the final alloy. This invention is directed to the solution of that problem.